The present invention concerns a connection device for optical fibres, comprising a first connector intended to be associated with at least a first optical fibre and a second connector intended to be associated with at least a second optical fibre which is to be connected to the first fibre.
There already exist many devices for connecting optical fibres together or effecting hybrid connections between two cables each containing at least one optical fibre and at least one electrical conductor. The optical fibres used to convey signals or information usually consist of a sheath surrounding a core made from refringent material, whose diameter has a value of between a few microns and a few tens of microns depending on whether it is a case of a monomode or multimode fibre. Under these circumstances, when the connection is to be made in a polluted fluid (liquid or gaseous) environment, for example containing particles of sand or dust or other fine inert or living particles, it is particularly important that, when two optical fibres are connected to each other, the front faces of the fibres to be joined are not soiled by one or more particles and/or that one or more particles do not remain captive between the front faces of the said fibres joined end to end. This is because, if this occurred, the transmission of the signals or information by the said fibres could be seriously affected thereby.
When it is a case of joining two optical fibres in air, it has already been proposed to place a drop of a fluid, in general in the form of a gel, having a refractive index equal to or very close to that of the optical fibres, on the end of each of the two optical fibres to be joined and then to place the two optical fibres end to end. Thus optical continuity, that is to say continuity of the refractive index, is ensured in the joining area of two fibres, even if there remains a small interstice between the two fibres after they are joined.
However, such a method is difficult to implement when the two optical fibres must be joined in a polluted fluid environment. This is because it is not always possible, in the polluted fluid environment, to manually put drops of gel on the ends of the fibres to be joined. Nor is it always possible to place drops of gel on the ends of the fibres to be joined whilst they are outside the polluted fluid environment, either because one of the two fibres is continuously in the polluted fluid environment and cannot be extracted therefrom, or because, even if a drop of gel is put at the end of a fibre whilst it is situated outside the polluted fluid environment, it is not certain that, after having been immersed in the polluted fluid environment, there will remain a sufficient quantity of gel at the end of the fibre at the time it is joined with another fibre. Such a situation may for example occur when it is a case of connecting optical fibres in an undersea environment, for example in order to connect a cable containing optical fibres to an undersea well head.
The purpose of the present invention is therefore to provide a connection device for connecting optical fibres in a polluted environment.
To this end, the connection device according to the invention is characterised in that one of the two connectors carries a reserve of a fluid having a refractive index equal to that of the optical fibres, and at least one pumping means which is connected to the said fluid reserve and which, in service, can be actuated in response to the connection and disconnection movements of the two connectors in order, at each connection/disconnection movement, to inject fluid into a space surrounding the front ends of the two fibres bringing them closer together or spacing them apart.
Thus, with the connection device according to the invention, when the two connectors are connected to each other in a polluted fluid environment, fluid (gel) having a refractive index equal to that of the optical fibres is injected into the space surrounding the front ends of the two fibres to be joined. The effect of this injection is to drive away any polluted fluid which might be between the front ends of the two fibres to be joined, and to clean the said front ends. After joining the two fibres, the gel thus injected provides optical continuity between the two fibres, even if there remains a small interstice between them after they are joined. In addition, when the two connectors are subsequently separated from each other, gel is once again injected into the space surrounding the front ends of the two fibres whilst they are separated from each other, so that, after their separation, the front ends of the two fibres remain protected by a certain quantity of gel, thus preserving the fibres against an attack by the polluted fluid environment, in particular by sea salt where the invention is applied to connectors intended to be used in sea water.
The connection device according to the invention can also have one or more of the following characteristics:
the first connector comprises a first fixed casing or base which has, in its end face turned towards the second connector, a first cavity which is open towards the said second connector and on the bottom of which there project on the one hand at least one fixed optical contact in the form of a socket, in which the first optical fibre is fixed, and on the other hand at least one pusher forced by a first spring towards the second connector;
the first optical fibre is provided with a first rigid contact piece which extends axially beyond the end of the fixed optical contact projecting in the said first cavity, and the fixed optical contact carries a protective cowl which, in the disconnected state of the connection device, covers the said first contact piece and is at least partially filled with the said fluid;
the protective cowl can slide on the fixed optical contact and has, in the region where it covers the free end of the first contact piece, at least two contiguous lips made from elastomer material, which can separate in order to allow the said first contact piece to pass when the protective cowl is subjected to a thrust directed in the direction of the connection movement of the second connector towards the first connector, counter to the force of a second spring forcing the said protective cowl towards the second connector;
the second connector comprises a second moving casing or plug, which can be fitted in the first cavity of the first casing and which has, in its end face turned towards the first connector, a second cavity which is open towards the said first connector and which contains at least one movable optical contact in the form of a socket, in which the second optical fibre is fixed, which is provided with a second rigid contact piece, the said movable optical contact being aligned axially with the fixed optical contact of the first casing when the second casing is fitted in the first cavity of the first casing, and being mounted so as to be able to slide with respect to the second casing between a first position in which the first and second contact pieces of the first and second optical fibres are spaced apart from each other, and a second position in which the said first and second contact pieces are mutually in contact;
the second contact piece is situated inside the movable optical contact in the form of a socket, which has, at its end directed towards the fixed optical contact, an entry convergence for guiding the first contact piece of the first optical fibre, and the first and second casings have abutment surfaces cooperating in order to limit the entry of the second casing into the first cavity of the first casing, so that, when the said abutment surfaces are mutually in contact and the movable optical contact is in its first position, the first contact piece is partially engaged in the entry convergence of the movable optical contact;
the second connector also comprises a wandering sub-assembly, which carries the said reserve of the said fluid and the said pumping means and which is able to move in the second cavity of the second casing in the direction of the connection-disconnection movement between a first position in which the said wandering sub-assembly is retracted in the second cavity of the second casing, and a second position in which it is partially emerged from the said second cavity;
the said wandering sub-assembly is coupled to the movable optical contact by an idle-movement connection and by a third spring so that, in a first part of the travel of the wandering sub-assembly in the direction of the connection movement, the movable optical contact is not driven by the said wandering sub-assembly and, in a second part of the said travel, the said wandering sub-assembly drives with it, by means of the third spring, the movable optical contact until the second contact piece of the second optical fibre comes into contact with the first contact piece of the first optical fibre;
the wandering sub-assembly comprises a body in which there are formed at least a first passage for the movable optical contact, a first chamber forming the said fluid reserve and a second, cylindrical, chamber which is connected to the first chamber by a second passage containing a first non-return valve allowing the fluid to pass only from the first to the second chamber, and a piston, provided with a second non-return valve, is disposed in the second chamber and divides the latter into a suction chamber, into which the said second passage opens out, and a delivery chamber which communicates with the said first passage through a third passage formed in the body of the wandering sub-assembly and with a chamber situated inside the movable optical contact in the form of a socket, in front of the second contact piece of the second optical fibre, by means of at least a fourth passage formed in the said movable optical contact;
the second non-return valve consists of a lip joint which surrounds the said piston and which allows the fluid to pass only from the suction chamber to the delivery chamber;
the piston is provided with a piston rod which extends in the delivery chamber and which projects outside the body of the wandering sub-assembly in the direction of the first connector and in alignment with the pusher of the first connector when the second casing is engaged in the first cavity in the first casing, and a fourth spring having lesser stiffness than the first spring is disposed in the suction chamber and forces the piston and the piston rod towards the said pusher, the said piston being actuated by the pusher when the wandering sub-assembly is moved from its first to its second position, and by the fourth spring when the wandering sub-assembly is moved from its second to its first position;
the second casing and the wandering sub-assembly of the second connector also comprises cooperating retention means for retaining the wandering sub-assembly in its first position in the second cavity of the second casing, and the second casing carries a control means which is actuated by the first casing when the said abutment surfaces of the first and second casings come into contact with each other, and which at this moment acts on the said retention means in order to put them in an inactive state such that the wandering sub-assembly can be moved from its first to its second position;
the second casing of the second connector has an anchoring ring made from elastomer material, which is fixed by one end to the second casing and which carries at its other end at least one anchoring element able to be attached behind a cooperating anchoring element formed on the first casing of the first connector when the said abutment surfaces of the first and second casings are mutually in contact;
to allow the movement of the wandering sub-assembly between its first and second positions, the second connector also comprises a manoeuvring ring which can slide on the second casing of the second connector and which is connected to the wandering sub-assembly in the second cavity by several radial connecting elements passing through oblong slots formed in the second casing;
the manoeuvring ring is sized and configured so as to closely surround the anchoring ring when the said manoeuvring ring is in a position corresponding to the second position of the wandering sub-assembly.